Stencil-sheet.



'nnirnn snares Parana. oration.

JAMES A. AMIBLER, 0F NATICK, MASSACHUSETTS.

STENCIL-SHEET.

No Drawing.

To all whom it may concern:

Be it known that I, JAMES A, AMBLER, a citizen of the United States,residing at Natick, in the county of Middlesex and State ofMassachusetts, have invented certain new and useful Improvements inStencil-Sheets; and I do hereby declare the following to be a full,clear, and exact description of the invention, such as will enableothers skilled in the art to which it appertains to make and use thesame.

This invention relates to stencil sheets which are commonly used fortypewriting duplication.

A form of stencil sheet now commonly used in typewriting duplicationconsists of a sheet of Yoshino paper coated with a coagulated colloid,such asgelatin, vegetable gums, Irish moss, etc., which colloids havebeen treated with glycerin, formaldehyde, and potassium bicromate.'Before a sheet of the above character can be used for type- Writingduplication it must be moistened to place the coating on the paper in.condition to receive the indentation of the type and to avoid cutting orbreaking the fiber of the paper. To properly moisten such a sheetrequires care and often occasions delay and inconvenience Further. allof the wellknown processes of making gelatin-coated stencil-sheetsemploy a large quantity of glycerin.

The primary object of the present invention is to provide a stencilsheet and process of making the same which will overcome the aboveobjections and produce a stencil sheet which is durable, efficient, andwill remain in condition for immediate use without nioistening.

In accordance with this ob one feature of the invention contemp coatinga sheet of open, porous material with a film of gelatin which isimpregnated with a hygroscopic metal chlorid, and then before the sheetbecomes hard treating it with a dilute solution of glycerin to keep itsoft and pliable. The glycerin is a hygroscopic, trihydric alcohol, andwhen used with a hygroscopic metal salt, such as calcium chlorid, thetwo ingredients tend to hold Specification of Letters Patent.

Application filed December 29, 1915.

Patented Dec. 24l,'1l9il&

Serial No. 69,225.

the sheet in a soft, damp condition so that the colloid will bepermanently in condition to be displaced by the indentation of the typewithout destroying the fiber of the paper base.

In carrying out the process, a paper base such as Yoshino or similarpaper having a loose,-coarse texture, is first passed through a bathcontaining. a solution having approximately sixteen parts of gelatin andthree and one-half parts of calcium chlorid dissolved in two hundred andtwenty-four parts of water, preferably distilled. These proportions maybe varied to quite a degree without materially altering the product.After the sheet has passed through the calcium chlorid bath and allowedto drain, it is next passed into a dilute glycerin bath containingapproximately four parts of glycerin and fourteen parts of water.

After the sheet has drained and dried it is soft and pliable and feelsslightly moist to the touch. The paper is very tough and is in acondition so that it may be used immediately to receive the impressionof characters of type. With the first treatment of gelatin and calciumchlorid, the paper base becomes thoroughly impregnated with the.

mineral chlorid and then the treatment with glycerin converts it to atough, pliable sheet. The hygroscopic properties of the chlorid inconjunction with those of the glycerin hold the colloid on the surfaceof the sheet permanently in a condition to be displaced by theindentation of type of a typewriter. The calcium chlorid also haspreservative properties in preserving the life of a colloid and greatlyreduces the amount of glycerin need-ed to keep the sheet in a moistcondition.

Having thus described my invention. what is claimed as new, is

1. The process of making a stencil sheet which comprises, passing a baseof open, porous material through a solution of gelatin and an alkalineearth chlorid. and subsequently passing the treated base through asolution of glycerin.

2. The process of making a stencil sheet Which-comprises, passing a baseof open, porous material through a solution containgelatin and three andone-half parts calcium chlorid in two hundred and twenty-four parts ofwater, and subsequently passing the sheet through a bath containing adilute glycerin solution having four parts of glycerin in fourteen partsof water.

' JAMES A. LER

